The present invention relates to a raster image serial printer for producing printed data by carrying out raster scanning with a serial recording head in response to bit map data received from a host computer.
A printing operation in a raster image mode is started when bit map data is store in a print buffer. Conventionally, when a printhead with 24 dot forming elements arranged in the subscanning direction (i.e., in the paper feeding direction) is used, for instance, printing cannot be started until data has been assembled and stored corresponding to all 24 dots in the subscanning direction and the number of print columns, i.e., a number of dots in the subscanning direction determined by the desired printing resolution. For this purpose, there has been provided a print image buffer having a capacity equal to the product of the number of print columns and the number of dot forming elements of the recording head.
The storage capacity of the print image buffer must be increased as the numbers of print columns and dot forming elements are increased. Therefore, to be able to print all types of data, it is necessary to either provide an image buffer having a large storage capacity or allow the printer to wait a relatively long period of time while the necessary data is assembled and stored in the print image buffer.